1. Field of the Invention
The invention relates to gravitational separators for liquid purification, more specifically to a baffle for the inlet and outlet ports of a septic tank.
2. Description of the Prior Art
A baffle is necessary at the outlet port of a septic tank, within the tank, to reduce the percentage of solid particulate matter in the liquid that exits the tank by way of the outlet port. The baffle generally reduces the percentage by directing the matter away from the outlet port, and by slowing or otherwise disturbing liquid flow to the port so that the effect of gravity on the particles is greater than the effect of the current which would otherwise carry them out of the tank.
A baffle is advisable at the inlet port of a septic tank, within the tank, to prevent flow across the top of the tank and to direct flow downward and across the length of the tank. This brings fresh microbes to the sludge at the bottom of the tank and stirs it, contributing to the fermentation of waste material in the tank.
U.S. Pat. No. 2,143,248, patented Jan. 10, 1939, by L. Otto, discloses a septic tank discharge port baffle arrangement for a metal drum septic tank of the type that receives toilet discharge directly in at the top.
A semi-cylindrical conduit, secured to the tank wall on each side of the port, extends vertically lengthwise from above the port to below the liquid level which is determined by the lower edge of the port. Two inclined plates, each secured by one of its side edges to the wall below the semi-cylindrical conduit, are wider than the radius of the conduit, so that they extend further from the wall than the conduit. The plates are oppositely disposed, upwardly and outwardly inclined in a T arrangement, and slightly spaced one from the other. Their top edges extend out as far on each side of the port as the conduit.
The plates thus form a V which directs rising sediment and gasses in a direction that is parallel to the wall and to the right and left of the opening formed at the bottom of the semi-cylindrical conduit and the tank wall, and the plates also form a funnel which directs falling sludge that may pass between the plates and the conduit, in a direction that is down parallel to the wall and to the right or left depending upon the orientation of the plates in the T.
For a concrete septic tank with a molded tee outlet, J. Quina, in U.S. Pat. No. 3,630,370, patented Dec. 28, 1971, discloses a deflector for use at the outlet end of the tank.
It is a biconic deflector, with its central axis concentric with that of the vertical pipe of the tee. It is located immediately below the bottom end of the vertical pipe which extends down into the liquid, held in place below the pipe by suitable holding means inserted into the bottom of the pipe. The biconic deflector has a top and a bottom apex, each with a cross sectional area that is smaller than that of the bottom end of the pipe, and its base is of a larger cross sectional area than that of the bottom end of the pipe.
Gas bubbles resulting from fermentation, which rise in the liquid and carry particulate matter, are deflected outward by the lower cone, so that they flow up toward the region around the vertical pipe. The bottom end of the vertical pipe has unencumbered space about its periphery so that gas bubbles carrying solid particles will flow around and upward rather than dam up against an encumbrance and back up into the pipe.
In lieu of the axially oriented biconic deflector, a corbel, which is an upward and outward stepped projection, is molded on the concrete wall below the bottom end of the pipe. Bubbles flowing over the lower sloped face of the corbel are directed away from the wall and pipe hanging in front of the wall, as they move upward. Bubbles flowing over the top slope of the corbel, travel to the unencumbered space around the vertical pipe, and upward.
U.S. Pat. No. 4,334,991, patented June 15, 1982 by E. Beede, discloses a septic tank baffle for concrete septic tanks, that is lighter and easier to install than concrete baffles.
Made from plastic such as polypropylene or the equivalent, about one eighth of an inch thick, the baffle takes the shape of a three sided trough which extends lengthwise from the top of the tank, flush with the cover, to a location below the level of liquid in the tank. It is positioned over the inlet or outlet port of the tank, to block lateral flow. The plastic is lighter in weight and less brittle than a concrete baffle.
For ease of installaton, the baffle has a pair of hanger straps which are parallel with the top edges of the side walls of the baffle where they are attached to it, extends beyond the walls and twists down at a distance from the walls, so that the baffle can be hung from the top of the septic tank wall which has the port.
The baffle is further fastened to the tank wall having the port, by a plurality of independent flanges which are attached to the baffle side walls, and are bent, extending away from the baffle wall edges. The flanges are resilient so that when they are anchored to the septic tank wall the side edges of the baffle are in tight linear sealing engagement with the wall of the septic tank.
In an alternate embodiment, the baffle is in the form of a flat plate instead of trough shaped, and extends to the tank walls which are on either side of the wall containing the port. The straps and flanges then attach to those tank walls.